Hepcidin is the master regulator of systemic iron homeostasis. The bone morphogenetic protein (BMP) signaling pathway is a critical regulator of hepcidin expression in response to iron and erythropoietic drive. Although endothelial-derived BMP6 and BMP2 ligands have key functional roles as endogenous hepcidin regulators, both iron and erythropoietic drive still regulate hepcidin in mice lacking either ligand or both. Here, we utilize mice with an inactivating Bmp5 mutation (Bmp5se), either …